In recent years, an electric vehicle and a hybrid electric vehicle, which have devices such as a motor and a battery and run by driving the motor with power stored in the battery, have begun to spread. In an electric vehicle, an outside power supplying device needs to supply power to the battery, and even some of hybrid electric vehicles are plug-in hybrid electric vehicles in which an outside power supplying device may supply power to the battery. In a vehicle wherein supplying power from outside to the battery is performed, a plug of a charging cable, which includes a power supply wire connected with an outside power supplying device, is connected with a connector device of a power supplying port provided in the vehicle. In addition, power supply from the power supplying device to the battery of the vehicle is performed via the charging cable.
Moreover, the power supplying device is connected with the vehicle via a control wire for sending and receiving a control pilot signal at the time of supplying power from the power supplying device to the battery of the vehicle, and charge control based on the control pilot signal is performed at the time of charging. Moreover, a communication system for superimposing another communication signal on communication, in which a control wire is used, has been proposed (see “SURFACE VEHICLE RECOMMENDED PRACTICE”, J1772 JAN2010, Society of Automotive Engineers, Inc., October 1996 (revised in January 2010), for example).